She's responding to your texts very quickly which is an IOI. But I think you need to step it up now, call her. Don'y text what you could say on a call. If you're not sure about whether she'll be available to talk, then send her a message prior along the lines of
Hey you sexy little thing, I'm going to give you a call in a bit, so get yourself feeling flirty, sexy, relaxed and tell me three interesting things about yourself/your day
Props to Belondon from another thread on the forums for the above line.
If she sends you a message or calls you without you prompting her to do so that's another IOI. Don't text too much though, leave her wanting more. Give her the gift of missing you (love David D and his work).